1. Field of the Invention
This invention relates to a copy-protected security print having a substantially regular background pattern of lines, dots, screen structures or the like.
2. Description of the Prior Art
It is well known to print documents to be protected from forgery with fine patterns constituting a background for other printed information. This background consists for example of families of lines, guilloches, dot patterns, screen structures and the like. Information, for example texts, logos or numerals, is then printed on this more or less regular background pattern.
Such a security print can be monochrome or colored. A colored security print is preferable to a black-and-white print because it is more difficult to copy. However, highly developed color copiers exist today which are capable of making remarkably good copies even of colored security prints. There are numerous measures for preventing or complicating the forgery of printed documents.